Communication devices within a wireless communications network may be wireless devices such as e.g., User Equipments (UEs), stations (STAs), mobile terminals, wireless terminals, terminals, and/or Mobile Stations (MS). Wireless devices are enabled to communicate wirelessly in a cellular communications network or wireless communication network, sometimes also referred to as a cellular radio system, cellular system, or cellular network. The communication may be performed e.g. between two wireless devices, between a wireless device and a regular telephone, and/or between a wireless device and a server via a Radio Access Network (RAN), and possibly one or more core networks, comprised within the wireless communications network. Wireless devices may further be referred to as mobile telephones, cellular telephones, laptops, or tablets with wireless capability, just to mention some further examples. The wireless devices in the present context may be, for example, portable, pocket-storable, hand-held, computer-comprised, or vehicle-mounted mobile devices, enabled to communicate voice and/or data, via the Radio Access Network (RAN), with another entity, such as another terminal or a server.
Communication devices may also be network nodes, such as radio network nodes, e.g., Transmission Points (TP). The wireless communications network covers a geographical area which may be divided into cell areas, each cell area being served by a network node such as a Base Station (BS), e.g. a Radio Base Station (RBS), which sometimes may be referred to as e.g., New Radio Node B (gNB), evolved Node B (“eNB”), “eNodeB”, “NodeB”, “B node”, or BTS (Base Transceiver Station), depending on the technology and terminology used. The base stations may be of different classes such as e.g. Wide Area Base Stations, Medium Range Base Stations, Local Area Base Stations and Home Base Stations, based on transmission power and thereby also cell size. A cell is the geographical area where radio coverage is provided by the base station at a base station site. One base station, situated on the base station site, may serve one or several cells. Further, each base station may support one or several communication technologies. The wireless communications network may also be a non-cellular system, comprising network nodes which may serve receiving nodes, such as wireless devices, with serving beams. In 3rd Generation Partnership Project (3GPP) New Radio (NR), base stations, which may be referred to as gNBs, may be directly connected to one or more core networks. In the context of this disclosure, the expression Downlink (DL) may be used for the transmission path from the base station to the wireless device. The expression Uplink (UL) may be used for the transmission path in the opposite direction i.e., from the wireless device to the base station.
Radio Network Architecture
The 3GPP is currently working on standardization of the 5th generation of a mobile radio access system, also called Next Generation Radio Access Network (NG-RAN). FIG. 1 is a schematic diagram illustrating an example of a Next-Generation RAN architecture. The NG-RAN may include nodes providing radio connections according to the standard for New Radio (NR), as well as nodes providing radio connections according to the Long-Term Evolution (LTE) standard. The NG-RAN may be connected to some network that may provide non-access stratum functions and connection to communication networks outside NR, such as the internet. This is here depicted in FIG. 1 as the 5G Core network (5GC), which comprises core network nodes Access and Mobility Management Function (AMF) and User Plane Function (UPF), as specified by 3GPP. As also depicted in FIG. 1, the different base stations, either gNB or Next Generation Evolved Node Bs (ng-eNBs) may be communicate with each other via a Xn interface, and with the core network nodes via Next Generation (NG) interfaces.
An evolved architecture for the RAN is foreseen, both for the LTE and the NR tracks of 5G. This includes a solution where the radio base stations may be split into parts for radio network control through Radio Control Units (RCUs) 21, packet processing through Packet Processing Units (PPUs) 22, Radio Rodes (RNs) with base-band processing through Radio Processing Units (RPUs) 23 and Radio Units (RU) 24. An example of the new architecture is shown in FIG. 2, indicating possible interfaces. The RCUs 21 and PPUs 22 are connected to the core network nodes 25 in the Core network.
The main task of a mobile radio network may be understood as that to provide good radio connections for mobile wireless devices to carry the services the users of the wireless devices may want to utilize. This process may be understood to involve finding the most suitable cells or antenna beams, which are herein simply referred to as beams, for every wireless device as it moves around. A beam may be understood as a spatial confinement of a radio transmission, which may refer to a narrow or wide angular spread of a power emitted from an antenna. This is today performed by requesting the wireless devices to measure strength and quality of radio signals from the serving beams, as well from neighbour beams. The results of the measurements are reported to the RAN, which may then take a decision on what beams may serve the mobile in the following. FIG. 3 is a schematic diagram illustrating a wireless device 31, in this particular example a User Equipment (UE), moving from a first cell 32 covered by a first group of beams 33 served by a serving gNB 34 to a second cell 35 covered by a second group of beams 36 served by a second gNB 37.
The performance of measurements involved in the process of providing radio coverage to a moving wireless device in a mobile radio network comprising beams involves the usage a great number of radio resources, reducing the capacity of a communications network, increasing its latency and consuming energy on the network side and the on the wireless device. This is particularly relevant for the wireless device, since it may drain battery, increasing the risk for a dropped connection. Moreover, the available bitrates will be lowered if the wireless device remains under poor coverage for a long time while it is performing the measurements.